1. Technical Field
This disclosure relates generally to an electron emission display, and more particularly, to and an electron emission display comprising spacers that are installed in a vacuum vessel that counteract compression of the vacuum vessel.
2. Description of Related Art
Generally, electron emission elements are classified into those using hot cathodes as electron emission sources and those using cold cathodes as electron emission sources. Known cold cathode electron emission elements include, Field Emitter Array (FEA) electron emission elements, Surface-Conduction-Emission (SCE) electron emission elements, Metal-Insulator-Metal (MIM) electron emission elements, and Metal-Insulator-Semiconductor (MIS) electron emission elements.
A FEA electron emission element includes electron emission regions, and cathode and gate driving electrodes for controlling the electron emission of the electron emission regions. The electron emission regions are formed of a material that can effectively emit electrons under an electric field under vacuum. Examples of such materials have a relatively low work function and/or a relatively large aspect ratio, such as Mo-based materials, Si-based materials, or carbon-based materials (e.g., carbon nanotubes, graphite, and/or diamond-like-carbon). Electron emission regions formed from Si-based materials and/or Mo-based materials are typically formed with a tip structure.
The electron emission elements are arrayed on a first substrate to form an electron emission device. The electron emission device is combined with a second substrate on which a light emission unit having a phosphor layer and an anode electrode are formed, thereby forming an electron emission display. In the electron emission display, the first and second substrates are sealed together at their peripheries using a sealing member, for example, comprising frit bars, to form a vacuum vessel. The interior of the vacuum vessel is evacuated to a pressure of about 10−6 Torr.
The pressure differential between the interior and exterior of the vacuum vessel results in a high compression force, which is proportional to the display size. Therefore, a plurality of spacers is provided in the vacuum vessel to counteract the compression force and to maintain a uniform gap between the first and second substrates. Typically, the spacers are formed from a dielectric such as glass or ceramic to prevent short circuits between the driving electrodes provided on the first substrate and the anode electrode provided on the second electrode.
In a typical electron emission display, heat generated from the driving electrodes is transmitted to the spacers. The heating causes a change in resistance in the spacers, which distorts the electric field around the spacers. Consequently the paths of the electron beams emitted from the electron emission regions and accelerated toward the anode electrode deviate from their intended paths and/or the electron beams are diffused.
These changes in the electron beam path around the spacers reduce the accuracy of color reproduction on portions of the display proximal to the spacers. Consequently, temperature variations within the display change the appearance of the display from its initial state.